The present disclosure relates to a gas-insulated circuit breaker and more particularly, to a gas-insulated circuit breaker having a structure allowing an insulation gas having been discharged from a breaker unit into an enclosure to be cooled.
In general, gas-insulated circuit breakers refer to devices for opening and closing a load device or interrupting a current in the event of an accident such as earthing or grounding, short-circuits, or the like, in power transmission and transformation systems or electrical circuits.
Such gas-insulated circuit breakers may be classified as vacuum circuit breakers (VCB), oil circuit breakers (OCB) gas circuit breakers (GCB) and the like, depending on an arc-extinguishing medium utilized therein.
In addition, a gas-insulated circuit breaker may have an insulating material provided within a pressure container, a movable contact and a fixed contact having a main contact and an arc contact in the interior of the insulating material, and the like, to thereby extinguish an arc generated at a point of contact between the main contact and the arc contact of the movable contact and the fixed contact.
FIG. 1 is a cross-sectional view of a gas-insulated circuit breaker according to the related art.
Referring to FIG. 1, the gas-insulated circuit breaker according to the related art may be configured of a fixed contact part and a movable contact part.
The fixed contact part may include a fixed contact member 20, a fixed arc contact member 30, and a fixed-side shield 25. The fixed contact part may further include a cylindrical fixed conductor part 10, and the fixed contact member 20 may be coupled to one end of the fixed conductor part 10.
In addition, in the fixed contact part, the fixed arc contact member 30 may be positioned within the fixed conductor part 10.
The movable contact part may include a movable contact member 50, a movable arc contact member 60, an external nozzle 71, an internal nozzle 72, and a movable axis 80. The movable contact member 50 may be inserted into the fixed contact member 20.
The movable arc contact member 60 may receive the fixed arc contact member 30 therein. The external nozzle 71 may be coupled to the inside of the movable contact member 50.
The internal nozzle 72 may surround the movable arc contact member 60 to be spaced apart from the movable arc contact member 60 and may be configured to be spaced apart from the external nozzle 71 to provide a transfer path for an insulating gas.
The movable axis 80 may have one end to which the internal nozzle 72 is coupled, and the movable arc contact member 60 may be coupled to the interior of the one end to which the internal nozzle 72 is coupled. In addition, in a case in which a device guiding a gas flow to the movable axis is not present, an insulation gas heated to a high temperature may be induced to flow within the movable contact part 40 overall.
Meanwhile, during a breaking operation of the gas-insulated circuit breaker, when the fixed arc contact member 30 and the movable arc contact member 60 are separated from each other, an arc may be generated due to a difference in voltage levels in both terminals thereof.
In this case, a cylinder 90 coupled to the movable axis 80 in order to break the generated arc may move back according to a withdrawal operation of the movable axis 80, such that an insulation gas filling the interior of the cylinder 90 such as SF may be sprayed into a space between the fixed arc contact member 30 and the movable arc contact member 60.
Here, the sprayed insulation gas may be in a high-temperature and high-pressure state due to the arc and a supersonic flow toward the fixed contact part and the movable contact part may be generated.
The insulation gas in a high-temperature and high-pressure state may be discharged from a breaker unit into an internal space of an enclosure.
However, in the case of the high temperature insulation gas, insulating properties may be remarkably degraded. The gas having degraded insulating properties may cause electrical breakdown between earths (between an enclosure and a breaker unit) and between phases (between multiphase breaker units).
Meanwhile, in a gas-insulated circuit breaker according to the related art, in order to facilitate the formation of an electrical field, that is, in order to generate a quasi-uniform electric field, the fixed conductor part 10 and a movable conductor part 40 are configured to have a cylindrical shape, and the enclosure accommodating the breaker unit therein may also be formed to have a cylindrical shape.
However, since the fixed conductor part 10 and the movable conductor part 40 configured to have a cylindrical shape as described above may have a narrow channel through which an insulation gas is discharged, a cooling degree of the insulation gas may be low when the insulation gas is discharged.